Metal fabricating compocnb



' controlled,

Patented Aug. l2, 194i attain METAL FABRIQCA'EHNG @QMPQHJND No Drawing. Application November 12, 1937, Serial N0. 174L222 l1 tlilaims. (Cl. tam-d8) The present invention relates to improvements in metal fabricating compounds such as cutting oils, drawing, stamping lubricants and the like. The nature of the improved composition will be fully understood from the following description.

Metal fabricating oils now on the market consist mainly of mineral or fatty oils, or mixtures of the same which have been sulfurized by the direct addition of sulfur or by the action of sulfur chlorides. Such compounds are for the main part dark in color, especially when sufficient sulfur is added to give maximum extreme pressure qualities. Some of the compounds may be initially light in colorbut they are found to darken quickly and soon lose their transparency. It has been recognized for some time that a transparent metal fabricating oil would be a dis tinct advantage, but so far anoil of this type which has the requisite extreme pressure proper! ties has not been produced.

It has now been found that excellent quality, permanently transparent, metal fabricating oil can be prepared by mildly sulfurizing an oil and then adding thereto a relatively small quantity of an ester of an acid of phosphorus. Sulfurization may be accomplished by treating the oil or other suitable materials with suitable sulfurizing agents such as free sulfur or sulfur halides, but the conditions of treatment should carefully be especially temperature and the amount of the sulfur introduced, so as to .obtain only a mild sulfurization; 'By this mild sulfurization is meant that insufficient sulfur is added to give the product the requisite extreme pressure properties and it has been found that this can be done while still maintaining a permanently light colored oil. To this product is then added the ester of a phosphorus acid such a tricresyl phosphate, phenol phosphate. or similar phosphites. Aliphatic alcoholic esters of the phosphorus acids may be employed but the most desirable substances are found to be alkylated aromatic esters of phosphoric and phosphorous acids. v

- The amount of sulfur incorporated should be carefully regulated within the limits of say .5 to 2.0% which, as will be "recognized, is much less than is usually present in currently solid metal fabricating oils, such as cutting oils. The amount of sulfur is so restricted, as indicated above, in order to produce a clean, transparent product. If sulfurlzation is accomplished with free sulfur, the required amount should be added to the oil and the mixture heated to about 250 to 300 F., but preferably not over the latter temperature as excessive darkening would begin to occur if the temperature rises much above that temperature. The heating is continued until the sulfur is permanently dissolved but prolonged heating beyond that point is not desirable.

In fact, it is preferred to cool the sulfurized product rapidly as soon as the sulfur has been permanently, incorporated which prevents loss of the beneficial effects of the sulfur.

The phosphorus ester may be added before sulfurization but is preferably added after. sulfurization and cooling. The amount preferred is within the range of .25 to about 2% and this is thoroughly admixed with the oil. If the amount of sulfur in the oil is in the lower range indicated above, for example at about 5%, then it is preferred to use an amount of the phosphorus ester in the upper range of that indicated, namely about 2%, and vice versa, but it is found that if the maximum extreme pressure qualities are desired, it is desirableto use both ingredients in the upper end of the range given.

The mineral oil to be sulfurized may be any type of mineral lubricating oil, whether derived from paraffinic, naphthenic or asphalt base self.

preferably with a viscosity from to 300 sec. Saybolt at 100 F. Solvent extracts obtained from lubricating oils are very desirable since these products are sulfurized more readily and can be sulfurized to a somewhat higher degree than the unextracted oils. By extract is meant that portion of the oil which is dissolved by solvent such as phenol, furfural, nitro benzene, and is characterized by being of lower viscosity index than the refined oil produced by the extraction. The best oil appears to be a blend of from 10 to 50% of a solvent extract with a nonextracted, paraffinic oil of good quality.

When using sulfur halides, particularly the monochloride, as the sulfurizing means, the temperature should be held down to F. during early stages and then gradually raised to 250-2'75 l t, and the chloride is to be added slowly with careful stirring. In this manner a clear oil containing, highly active sulfur compounds is produced which can be blended with the ester of the phosphorus acids to give an excellent cutting oil.

Instead of sulfurizing the mineral oil itself of this type include fatty oils, particularly those containing unsaturated linkages such as lard oil and the like which sulfurize more readily than does the unsaturated mineral lubricating oil it- Terpenic materials such as pine oil or its fractions, or rosin fractions or derivatives such as esters of abietic acid, methyl or ethyl abietate or resins produced by condensation of such esters,

tives may be employed. Such materials maybe sulfurized by direct addition of sulfur or by the action 01' sulfur halides as indicated before.

The following examples are given tomore fully describe the nature of the products made by the present invention.

Example I To illustrate the extreme pressure qualities of an oil produced by the present invention, several samples were made up as follows: Sample No. 1 was a straight mineral oil distillate having a viscosity of 100 sec. Saybolt at 100 F. Sample No. 2 was made from this oil by the addition of 2% of tricresyl phosphate. Sample No. 3 was made by sulfurizing the mineral 011, Sampl No. l, by heating the same with 2% sulfur at a temperature of 300 F., for /2 to 1 hour until the sulfur was permanently dissolved. The oil was then immediately cooled to room temperature and 2% of tricresyl phosphate was added. These three products were then submitted to tests on the Almen machine, using steel to steel bearings, with the following results:

carried These data indicate that the first sample, carried 3 or 4 weights in different tests, which was equivalent to loads of 3,000 to 4,000 pounds/sq. in., but this straight mineral oil failed when additional load was applied. Similarly, Sampl No. 2 carried about 10,000 pounds but failed when the load was increased to 11,000 pounds/sq. in. Sample No. 3, on the other hand, carried 15,000 pounds/sq. in., the full load of the test, and did not fail at the end of the test. Sample No. 3 was an extremely clean, transparent oil, free from objectionable odor and without any undesirable action on the slcln.

Example II Cutting oils have been tested and evaluated successfully by a method described by O. W. Boston in a paper presented to the sub-committee on cutting fluids of the A. S. M. E., at the Cin- Weight life decreases and while the difference between diirerent testsis often-quite small at th very high speeds of the test, these small differences are magnified into verylarge differences in tool life. at usual commercial cutting speeds by means of the equation which has been shown by Boston to be satisfactory. The speeds at which the tests are usually carried out are from to 180 ft./min., while the commercial speeds vary from 20 to ft./min., depending on the type of work. An oil of the type described in Example I was found to have a tool life equation as follows:

This equationindicates that at a speed of ft. per minute the tool life is about 4 minutes; at a speed of 140 ft. per minute it is 23 minutes; at 110 ft. per minute it is 509, and at 100 ft. per minute it is calculated to be 1724 minutes, which indicates a long tool life when the tool is used at production cutting speeds.

In all of the tests the oil gave an excellent finish to the work, remaining transparent throughout the operation and having a pleasant odor which is quite different from most of the sulfurized materials; also, it did not injure the skin of the operators.

The present invention is not to be limited to any theory of either of the ingredients nor to any particular amounts of those materials, but only to the following claims in which it is desired to claim all novelty inherent in the invention.

We claim:

1. An improved metal fabricating oil comprising a mildly sulphurized mineral lubricating oil containing not more than 2% of added sulfur in a soluble, corrosive form and an oil-soluble ester of an acid of phosphorus, the compound being clean and transparent.

2. An improved metal fabricating oil comprising a mildly sulphurized mineral lubricating oil distillate, containing from .2 to 2% of sulfur in the form of a corrosive compound soluble in the oil and an oil-soluble ester of a phosphorus acid, the compound being clean and transparent.

3. Product according to claim 2 in which the corrosive sulfur compound results from the direct action of a sulfurizing agent on the mineral oil in mild sulfurizing conditions.

4. Product according to claim 2 in which the ,oil contains up to 2% of an ester of phosphoric acid.

5. Product according to claim 2 in which the oil contains .5 to 2% of an aromatic ester of phosphoric acid.

6. Product according to claim 2,in which the compound contains .5 to 2.0% of an alkylated much above those ordinarily used commercially,

so as to obtain a rapid destruction of the tool. When the speed in feet/minute is plotted against the tool life in minutes, it is found that the data fall on a curve of the following type: VT"=K where T:Too1 life in minutes V=Cutting speed of the test in ft./min.

n=Is an exponent varying from about .08 to .14

and

K=The constant varying somewhat, but usually about 180.

As the speed is greatly increased, of course tool aromatic ester of phosphoric acid. 7. Product according to claim 2 in which the oil contains .5 to 2% of tricresyl phosphate,

8. Product according to claim 2 in which the oil contains .5 to 2% of an ester of phosphorous acid.

9. Product according to claim 2 in which the oil contains .5 to 2% of an aromatic ester of phosphorous acid.

10. Product according to claim 2 in which the oil contains .5 to 2% of an alkylated ester of phosphorous acid.

11. Product according to claim 2 in which the oil contains .5 to 2% of tricresyl phosphite.

ARNOLD J. MORWAY JOHN C. ZIMMER. 

